It can be difficult to effectively ventilate large, wide-open areas of a building such as those areas typically found in warehouses and factories. Ductwork can be expensive and impractical in some applications, so as a low-cost alternative, a number of ceiling fans might be installed simply to keep the indoor air circulating.
An area can be ventilated by a large number of small fans or a fewer number of large fans. Either option has its advantages and disadvantages. Smaller fans can be easier to install between rafters, sprinkler heads, hanging lights and other obstacles found in some buildings. Small fans might also be strategically located to focus the ventilation where it is most needed. In buildings with high ceilings, however, small fans might not have the capacity to discharge air at a volume that can effectively reach the area near the floor where the occupants could appreciate the airflow, thus small fans might be almost worthless in some cases.
Larger fans might be able to discharge air at a volume and velocity that can reach the floor, however, large fans require more radial clearance, thus they can be more difficult to install between obstacles. If a large fan is lowered so that the fan blades rotate underneath the obstacles, the fan might be so low that it creates a focused draft directly below the fan rather than broadly distributing the air. Increasing the speed of the fan can worsen the focused draft problem. Decreasing the fan speed can eliminate the draft, but operating below the fan's rated speed can be an inefficient use of the fan. In addition, large fans are inherently heavier and may require creative means for ensuring that the fan and its various parts remain intact.
Consequently, a need exists for an industrial ceiling fan that overcomes the aforementioned drawbacks of both small and large fans.